Vortex Shedding around a Simplified Model of an Engine Installation at Low Speed/High Angle of Attack Flight Conditions

Abstract

The flow around a model geometry of an engine installation equipped-wing, for low speed/high angle of attack flight conditions is investigated by means of URANS computations and 3C–PIV measurements. Environmental concerns such as pollution-reducing and engine noise attenuation have to prompt engine manufacturers to design UHBR (Ultra High Bypass Ratio) turbojets. This requires to increase their diameters leading to a close-coupled configuration. As a consequence, aerodynamic interaction between the engine and the aircraft becomes more critical during take-off and landing phases and a complex unsteady vortex dynamics is generated on the wing extrados. This complex flow causes a drop in aircraft aerodynamics performances, characterized by a loss of maximum lift and an increase of drag, resulting in a loss of climb gradient. This work deals with the flow that develops around a simplified geometry of an engine/pylon/wing installation. This study is achieved on the basis of 3C–PIV measurements and URANS computations data. As a first step to a more comprehensive knowledge of this complex physics, the study is initially conducted at a Reynolds number of 200000, based on the chord wing (c = 0.1m) and on the free stream velocity (U∞ = 30m/s). Several angles of attack (α) and slip angles (β) of the model have been investigated. Vortex dynamics is precisely described with a vortex tracking post-processing algorithm. A precise description of this vortex dynamics interacting with the wing boundary layer will allow to design some future active flow control strategies.